Last week, Google announced an upgrade to its Web-based Gmail service for users of the iPhone and Android-powered devices. The new service has an easier-to-use interface, loads and searches e-mails faster, and has the ability to check e-mails even without access to a wireless signal.

More significant than the interface, however, is the underlying technology that enables it. Google took advantage of features of the browsers running on both platforms to create a Web application that looks and feels like one that has been downloaded onto the device. Representatives from Google claim that this is just the beginning. The company hopes that the new mobile Gmail will kick-start a trend in mobile Web apps with developers using the Internet to build and deploy more powerful applications.

According to some analysts, this approach to mobile development could have large implications for the way that developers distribute their software and the way that people buy it. It’s even possible that more-powerful mobile Web apps could undercut some of the business of Apple’s App Store, says Chetan Sharma, an analyst who runs his own consulting firm in Issaquah, WA.

“From the user’s point of view, one of the problems with the App Store is discovery of content and apps,” says Sharma. “It could be easier to discover mobile software living outside the App Store using a browser.” The user won’t care whether the app is running out of a browser or is running directly on the phone, Sharma says, “as long as you get the same sort of experience.” A developer also has much more control over the distribution of the software, and she can keep the revenue it generates instead of splitting it with a third-party distributor like Apple.

More powerful mobile Web apps won’t become widespread overnight, though. Google is leveraging Web browser capabilities that exist on a relatively small number of devices: the iPhone, the iPod Touch, and the current (and forthcoming) Android phones. These devices run browsers based on the open-source Webkit code base, which has already implemented features required under the forthcoming Web programming standard HTML 5.

These features include a graphics tool called Canvas, “persistent storage,” and an “application cache,” explains Shyam Sheth, product manager on Google’s mobile team. Canvas is something of an alternative to the popular Adobe Flash software that’s commonly used to create graphics and animation on the Web. Persistent storage provides a way for data, originally on a remote server (such as Google’s e-mail servers), to be stored locally, on the device. The HTML 5 application cache keeps important information about an application on the device that allows it to open quickly, as if it were running directly on the hardware instead of remotely. The iPhone version of Gmail uses only HTML 5, whereas Android uses a combination of HTML 5 and Gears (a Google software add-on that enables its Web apps to run offline).

Sheth says that there are a number of advantages for developers who build mobile applications via the Web. While there are only three major operating systems for desktops that developers need to learn, there are tens of mobile-device platforms with various different requirements. Applications can be built on the Web and need to be modified only slightly for different mobile devices. “Given the number of platforms we have in the mobile space,” says Sheth, “we really need a unifying platform . . . That’s why Google is so heavily investing in the Web becoming the common platform.”

Sheth notes that many developers are already familiar with writing software for the Web. Another advantage of mobile Web apps, he says, is the ability to roll out an update without needing to deploy new code to individual devices. This means that updates can happen more frequently and without the need for users to take action.

Nonetheless, mobile Web apps may have limited capabilities in the near future. “Apps that will work in this environment will be more text heavy or static,” says Sharma. They won’t be the type of apps that need to be constantly updated from a server. “But when you get into games or applications that require [device] support, it becomes tougher to develop applications that are browser only,” he says.

In the long term, there may be little difference between mobile Web apps and the platform-specific ones that run on today’s devices, says Matt Womer, who is the World Wide Web Consortium’s Mobile Web Initiative lead for North America. He notes that users of the iPhone and Android can create widgets that represent the Gmail Web app and place them in the phone’s application palette. “The gap between an app and a Web app is narrowing,” Womer says. “The future will be more Web apps than platform-specific applications that require some sort of specialized knowledge to program. It’ll be interesting to see how this shakes out with the app stores when everyone starts launching Web apps,” he adds.

Womer says that forthcoming features of HTML 5 will be available in the coming months, although it could take years for the entire standard to be approved. He notes that geolocation is already available, enabling programs in a phone’s browser to tap into the location of a user. And some future features could allow Web software to access data from accelerometers, light sensors, and the microphone.

“I’ve been doing mobile stuff for years,” Womer says, “and this is the fastest rate that I’ve seen things go in the mobile world.”